305/65R17 vs 305/70R17
305/70R17 is outside the ±3% rule as a replacement for 305/65R17: the diameter differs by +3.68%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
Speedometer and odometer
With 305/70R17 on a car calibrated for 305/65R17, the speedometer reads 57.9 mph when you're really doing 60, and the odometer under-counts by 3.7%.
| Speedo shows | Actual speed |
|---|---|
| 30 mph | 31.1 mph |
| 45 mph | 46.7 mph |
| 60 mph | 62.2 mph |
| 70 mph | 72.6 mph |
| 80 mph | 82.9 mph |
Other sizes close to 305/65R17
- 305/65R17 vs 265/70R17-3.08%
- 305/65R17 vs 285/70R17+0.30%
- 305/65R17 vs 245/75R17-3.50%
- 305/65R17 vs 265/70R18-0.01%
- 305/65R17 vs 235/80R17-2.47%
- 305/65R17 vs 285/75R16+0.68%
- 305/65R17 vs 285/65R18-0.07%
- 305/65R17 vs 255/70R17-4.77%
- 305/65R17 vs 255/75R17-1.69%
- 305/65R17 vs 295/70R17+1.99%
- 305/65R17 vs 305/70R16+0.62%
- 305/65R17 vs 285/75R17+3.74%
Questions
Can I replace 305/65R17 with 305/70R17?
305/70R17 is outside the ±3% rule as a replacement for 305/65R17: the diameter differs by +3.68%, so the speedometer, odometer and ABS calibration will be off and clearance needs checking.
What's the difference between 305/65R17 and 305/70R17?
305/70R17 is 1.20" taller and 0 mm wider; the sidewall is +0.60". At an indicated 60 mph you'd actually be doing 62.2 mph.
Will 305/70R17 fit on 305/65R17 wheels?
Both use a 17" rim, so the wheel diameter matches; check the wheel's width range for a 305 mm tire and the fender clearance.